Brush both sides of each chicken breast lightly with olive oil.
In a small bowl, combine the paprika, garlic powder, onion powder, salt, and black pepper.
Sprinkle the seasoning mix evenly over both sides of each chicken breast.
Heat a grill pan over medium heat, or preheat an outdoor grill to medium-high.
Place the chicken on the grill and cook for 6 to 8 minutes per side, depending on thickness, until the internal temperature reaches 165°F.
Remove the chicken from the heat and allow it to rest for 5 minutes.
In the meantime heat the olive oil and butter in a large skillet over medium heat.
Add the chopped shallot to the skillet and cook for 2 minutes until softened.
Add the sliced mushrooms in a single layer and allow them to cook undisturbed for 3 to 4 minutes to develop color.
Stir the mushrooms and continue cooking until golden brown and tender, about 6 to 8 minutes total.
Stir in the minced garlic and cook for 30 seconds.
Add the parsley, dill (if using), and lemon juice to the skillet. Cook for 1 more minute, then remove from heat.
Place the grilled chicken breasts on a serving platter and spoon the sautéed mushrooms generously over the top.
Serve immediately.
Notes
Tips and Tricks
Pat the Chicken Dry. Removing excess moisture from the surface of the chicken before seasoning helps it develop a better sear on the grill. Skip this step and the chicken steams instead of getting color.Don't Skip the Rest Time. After removing the chicken from the grill, let it rest for 5 minutes before cutting or serving. This keeps the juices inside the meat instead of running out when you slice it.Cook the Mushrooms in a Single Layer. Crowding the mushrooms causes them to steam instead of brown. If your skillet is on the smaller side, cook them in two batches.Use a Meat Thermometer. Chicken is done when the internal temperature hits 165°F. A meat thermometer takes the guesswork out of it and prevents overcooking.Add the Garlic Last in the Mushroom Pan. Garlic burns fast. Adding it after the mushrooms are already golden keeps it from turning bitter.Pound Thick Chicken Breasts to an Even Thickness. If your chicken breasts are very thick, place them between two sheets of plastic wrap and pound them to an even thickness before seasoning. This helps them cook evenly from edge to center.
Storing and Reheating
Store - Store leftovers in an airtight container in the refrigerator for up to 3 days. Keep the chicken and mushrooms together for the best flavor.Freeze - To freeze, place cooled chicken and mushrooms in a freezer-safe container or zip-top bag and freeze for up to 2 months. Thaw overnight in the refrigerator before reheating.Reheat in Skillet - Place a serving in a large skillet over medium-low heat with 1 to 2 tablespoons of water or chicken broth. Cover and warm for 4 to 5 minutes, stirring occasionally, until heated through.Reheat in Microwave - Place the chicken and mushrooms in a microwave-safe dish. Cover with a damp paper towel and heat in 30-second intervals until warmed through. Avoid overheating to keep the chicken from drying out.